Scientists have figured out why your skin tenses up and
your teeth chatter when an icy blast of wintry wind whips
past: The brain’s wiring system monitors the temperature
of the skin and decides when the shivering should commence.
Shivering is one of the many automatic and subconscious
functions that the body performs to regulate itself. Other
so-called homeostatic functions include the adjustment
of breathing rates, blood
pressure, heart
rate and weight regulation.
Shivering is essentially the body's last-ditch effort
to keep itself warm.
"Shivering, which is actually heat production in
skeletal muscles, requires quite a bit of energy and is
usually the last strategy the body uses to maintain its
internal temperature to survive in a severe cold environment,"
said Oregon Health & Science University research fellow
Kazuhiro Nakamura.
Nakamura and his colleagues studied rats and traced
the shivering sensory pathway from the rodents' skin
to specialized cells in a portion of the brain called
the lateral parabrachial nucleus. These cells can then
transmit information to another part of the brain, the
preoptic area, which decides when the body should start
shivering.
The rat research is thought to directly apply to humans
because previous research has shown many parallels in
how the two species sense and regulate heat.
The study, detailed in an online edition of the journal
Nature Neuroscience, also found a connection
between conscious and subconscious cold-sensing mechanisms.
"One fascinating aspect of this study is that it
shows the sensory pathway for shivering, which can be
thought of as brain wiring, is parallel but not the same
as the sensory pathway for conscious cold detection,"
Nakamura said. "In other words, your body is both
consciously and subconsciously detecting the cold at the
same time using two different but related sensory systems."
The sensory system the researchers found in the brain
also seems to operate other cold-control mechanisms, such
as the restriction of blood flow to the skin, Nakamura
said.
